The Little Trailer That Could

By Claire Wolfe

January 1, 2005

In these parts, about every third homestead has a trailer sitting in its driveway or its backyard. A few of these are brand-new highway palaces, bigger and fancier than most Hardyville houses. But most are older travel trailers ­ the kind of thing you can pick up for $750 or a thousand bucks in the weekly Wooden Nickel or Hardyville Horsetrader or whatever your local freebie paper is called.

I've been staying in one of these things myself lately, despite a lifetime's violent aversion to what a trailer-park-owning friend calls their Herb Tarlek decorating schemes. And you know, they have possibilities. Not only the obvious possibilities for camping or guest-house use. But possibilities for preparedness.

A trailer, when you think about it, can pretty easily be turned into a large and versatile super bug-out-bag or 72-hour kit for use in emergencies. Or even for longer-term SHTF situations. In some cases (like hurricanes, where you get advance warning) you might be able to drive your preparedness trailer away to safety. In others, simply walk into the backyard and move into it when the power or water goes out in your home.

Every self-contained trailer has ample water and sanitation onboard to get a small (and careful) family through a week of use. These things are also marvels of storage ­ plenty of places to tuck at least modest supplies of dried lentils and hand-crank combination radio-flashlight-battery-charger-kitchen-blender thingies.

Their propane tanks can get you through a week or so of heat and cooking, even in a dark and dire winter. They've got stoves, refrigerators, and sinks. And they've usually got beds enough to sleep a small Boy Scout troop.

You could spend a lot of time, money, and planning on preparations like that. Or you could open this Wednesday's edition of the Thrifty Nifty.

Oh yeah, trailers do have drawbacks (as my park-owning friend also points out). Aside from looking from the outside like large, mobile garbage cans, they have an astonishing ability to be both suffocatingly air-tight and so drafty that ice forms on their inside walls even as the heater cranks with all its might. When a very tall friend came to visit not long ago, he had to do an Igor imitation just to walk from the kitchen to the bathroom.

And everybody knows what happens to the dreaded trailer park in every tornado, hurricane, and earthquake. Read the news and you get the impression that moving into one of those places is a slow, strange, but absolutely certain, means of committing suicide.

But that, of course, is the fault of the park, not of the trailer. Avoid milling herds of trailers and you're usually all right.

The one great weakness most trailers have for preparedness is their electrical systems.

Trailers commonly come with two separate but complementary electrical setups ­ one that operates lights and plug-in appliances on regular household 120-volt AC current and another that operates a second set of lights and some built-in appliances on 12-volt DC current from a battery.

This sounds great. Backup systems! Redundancy! A preparedness planner's dream. Except that the 120-volt system won't work unless you're plugged in to a working outside power source. Which you probably won't be if the SHTF or the hurricane hits the coast. And the standard 12-volt system (as I found to my chilly discomfort one night when the battery lost the ooomph to fire up the igniter on the built-in propane heater) is good for very limited use before the battery must be recharged.

Some of those highway palaces now come with solar panels and far more versatile electric systems. (I'm not talking to you people rich enough to afford such things.) But older and less expensive trailers need some do-it-yourselfing.

If your trailer is parked permanently, you may be able to create a full-scale solar or wind system for it. But I'm in the process of coming up with a more modest (but also less expensive), "even-a-girl-can-do-it" retrofit. For a few hundred dollars, this system will give my very own Herb Tarlek Haven a bit of power independence in two stages.

Stage One (being completed this week):

Will give me about two days of fully independent power when I'm unplugged from the local AC power system.

Will let me run up to three 120-volt AC appliances off battery power at any time.

With the Stage One system I'll be able to heat the place, use my laptop computer, turn on lights ­ even run a low-wattage microwave oven, should I decide to get that wild and crazy-- without any grid connection. Since the local power system is actually an off-grid solar system belonging to friends, Stage One will also allow me to use the microwave while I'm connected to their system without putting a major suck on their batteries (which even a small microwave does). On cloudy days when their solar panels aren't charging with full effiency, it will allow me to avoid drawing power they need for themselves.

Stage Two will do all of the above. But it will also let the trailer generate solar power to charge its own batteries. Right now I'm focused on Stage One.

This portion of the retrofit requires:

Two deep cycle marine/RV batteries. ($60 each on sale; that trailer from the Parsimonious Penny probably already has one, but it's not a good idea to mix old and new batteries, or batteries of different makes.)

One 1,000-watt inverter, designed to convert battery power to household 120-volt AC. ($75 on eBay) (See more on important inverter specs below.)

Two short power cables (one red, one black; 4-gauge) to connect the two batteries to each other. ($10.60 at the local NAPA)

Two longer power cables (one red, one black; 4-gauge) to connect the inverter to the battery. ($12 for both at the local NAPA)

Both batteries currently rest on a board laid across the trailer hitch. (I'll eventually build a small battery box or shed to keep them out of the weather and keep them warm; batteries work best at cozy room temperature.)

One battery ties into the trailer's existing 12-volt system.

The short cables connect the two batteries to each other: red cable connects the positive terminals to each other; black cable connects the negative terminals to each other. This like-to-like connection is called a parallel connection. Connecting in parallel gives your two-battery system twice the storage capacity as one battery.

The two longer cables connect the batteries to the inverter: red cable connects the positive terminal of the other battery to the positive terminal of the inverter; black cable connects the negative terminal of one battery to the negative terminal of the inverter.

The batteries are outside the trailer. The inverter sits inside. My cables pass through a sliding window, which I then neatly duct-taped over to prevent drafts; you could also drill a hole in the trailer wall to insert the cables, then fill it with caulk or expanding foam. insulation.

And that is it.

A few safety precautions offered by reader David Newton, who has built his own (much larger scale) trailer self-sufficiency system:

Make sure the 12-volt system in your trailer is protected by one or more fuses. If your trailer's system has no fuse, you should add an inline fuse to the red cable that connects the battery to the 12-volt system.

If your inverter doesn't have fuses (and many small ones don't), then you should also add a 110-amp Class T fuse to the red (positive) cable between the battery and the inverter. This is a special DC fuse, not a common AC fuse. (The National Electric Code requires a disconnect (a breaker), but many trailer owners go with the simpler, cheaper fuse.)

The longer your cables, the heavier your wire should be ­ but the rule is that shorter cables are better cables. If the appliances you need to plug in are far from the batteries, it's generally better to place the inverter near the batteries and run a sturdy (at least 14-ga) extension cord between the inverter and the appliances than to have a long cable between the inverter and the battery.

The system I've described is ungrounded, but many trailer owners operate this way without problems.

My inverter is from Tripp-Lite, a company well-known for serving long-haul truckers who want the comforts of home while on the road. It's a super-reliable brand (as is Xantrex), but I chose it primarily because this model has three electrical outlets, while most small ineverters have only two. And because its four built-in standard automotive fuses saved me $50 and the work of cutting and soldering my cables. And it was an eBay bargain.

You should also look for an inverter that has a low-voltage warning and a low-voltage disconnect (LVD) to shut off power to the inverter if the battery voltage gets dangerously low. Depleting your batteries too deeply damages them and significantly shortens their life.

It's important to get marine/RV deep-cycle type batteries -- not regular car batteries. You might see them side-by-side in the auto-supply department and be tempted by the lower prices on the car batteries. But those are made primarily for starting engines, then simply going inert and recharging. Deep-cycle batteries are made for running things. For hours, if need be.

I can run my small microwave (500 watt), laptop computer (70 watt), and a flourescent reading light (15-watt) on the inverter all at the same time ­ which is all I expect to need to do. Should I need to run power tools, I can unplug the household equipment and have at it. And I can go at it for several days steadily without being plugged in anywhere.

Stage Two, which I'll probably undertake within the year, will add a 75-watt solar panel and a charge controller to the Stage One system. The charge controler ensures that the power goes into the batteries at a measured pace, and also makes sure the solar panel won't suck the power back out of the batteries at night. If the single 75-watt panel doesn't turn out large enough to suit my small needs, I can easily add another panel.

With the Stage One system, the trailer remains fully mobile but has only a few days of independence (assuming fairly heavy use of computer, heater-igniter, etc. and extremely sparing use of the microwave).

The trailer could still be mobile after Stage Two if the panels are cleverly mounted to the trailer's roof or body and can fold down out of the way for travel. I don't plan to move the trailer, so I'll set the panels in fixed frames, anchored to Earth.

I'll keep you posted about how this system works (either in a future column or on my blog). But eventually, even if it takes some refinements (which I'm sure it will), I'll have a power-independent trailer.

My thanks to David Newton for reality checking both this article and my own trailer plans. His advice made this system safer and smarter. Any errors are strictly my own. Thanks also to Randall the Dreamer for his observations on the strange and quirky nature of trailers.

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